1. Field of the Invention
The present invention is directed to a pressure pulse generator having an electromagnetic pressure pulse source, and in particular to such a pressure pulse generator having a pressure pulse source of the type having an electrically conductive membrane and an electrical coil arrangement for driving the membrane, with a central bore, for accepting a component such as the ultrasound application of an ultrasound locating system, extending through the membrane and through the coil arrangement, with a further component, such as a housing, arranged in the region of the outer edge of the coil arrangement.
2. Description of the Prior Art
Acoustic pressure pulse generators of the type described above are used for medical purposes for, for example, treating stone, bone and tumor pathologies. Such acoustic pulse generators are also used for non-medical purposes. In any case, the pressure pulse generator is acoustically coupled by a suitable coupling element to the subject which is to be charged with pressure pulses, and the subject and the pressure pulse generator are aligned relative to each other so that the pressure pulses pass through the target region of the subject.
European Application 0 301 360, corresponding to U.S. Pat. No. 4,928,672 describes a pressure pulse generator of this type. In such pulse generators, as is conventional, the housing as well as the ultrasound head are at ground potential. The coil is a flat coil having spiral turns, and has an inner terminal and an outer terminal. Either the outer terminal, which is adjacent the housing, or the inner terminal, which is adjacent the ultrasound applicator, is also at ground potential. The other terminal of the coil arrangement is supplied with high voltage upon activation of the pressure pulse source, to cause the generation of pressure pulses by interaction with the flexible, electrically conductive membrane.
This arrangement has the risk of voltage arcing between the inner terminal of the coil arrangement and the ultrasound applicator, or between the outer terminal of the coil arrangement and the housing. Because such voltage arcing not only decreases the useful life of the pressure pulse generator, but also can lead to destruction of the ultrasound applicator, an insulating distance of sufficient size to avoid voltage arcing is provided between the outer terminal of the coil arrangement and the housing, or between the inner terminal of the coil arrangement and the ultrasound applicator. If an ultrasound applicator of a specific diameter is to be used, an increased need for installation space arises as a consequence of the aforementioned insulating distance which must be provided, regardless of whether the outer terminal or the inner terminal of the coil arrangement is at ground potential.